This is a discussion on High Altitude Tuning within the High Altitude Tuning forums, part of the Engine Modifications category; Ok, that is what I was thinking, but my butt dyno has been wrong before...

Quick question

Okay, since I live in Colorado Springs, should I hav emy STi tuned? I was wondering that since the stock ECU was most likely not tuned for this kind of altitude. And if I should get it tuned, where is a good shop to go to.

"I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the blanket of the very freedom that I provide, then questions the manner in which I provide it."De Oppresso Liber

Im planing on doing the new turbo, front mount, fuel rails, fuel injectors, waste gate, bov, headers,upipe, re tune the chip and oil catch can...any other suggestions or things i should do or parts i should use when i decide to change the turbo??

Okay, since I live in Colorado Springs, should I hav emy STi tuned? I was wondering that since the stock ECU was most likely not tuned for this kind of altitude. And if I should get it tuned, where is a good shop to go to.

+1 on this. My bugeye runs like crap in open loop, can/does the dealer flash high altitude maps? I did find an oddball spark plug ( different brand and heat range from other 3 ) that seems to be helping else I am too accustomed to my old V8 Hemi. 300wtrq at 2600rpm would make anything feel sluggish....

Toulca Mexico 8600ft!!!

hi Guys
I'm moving my stock 02 impreza WRX to my new home in Toluca Mexico where she will be unique! she has always been at sea level, any suggestions on tuning?
It is quoted that all cars lose at least 25% POWER at this alt....

Tru3th - Look into high altitude turbos. They should have compressor maps with higher pressure ratios (2.5-3.0 OK), and low flow surge lines. Surge is a possibility at high altitude much more than at sea level due to the lower density air and higher boost we typically run. Remember 20 psi at 5280 is a pressure ratio of around 2.8, compared to a sea level ratio of 2.36. Some turbos really won't like that, overspeeding and ruining the bearings.

ktmrider - Sluggishness, especially if you can tell it's worse in open loop, is probably due to a mixture that's too rich. I suggest you get some wideband readings, whether installed and on the road, or even a tail pipe sniffer on a dyno. Tailpipe will run around 1.0 to 1.5 more lean than pre-cat, but you'll get an idea how rich it's running. Are you tuned, or is this the ECU? If you're just getting used to turbo lag, then welcome to the club. De-restricting your uppipe and exhaust will help immensely.

davidcommons - high altitude costs a lot of power. The SAE correction on the dyno usually adds around 50 hp to correct to sea level (stage 2 STi). The good news is that you can take more advantage of the turbo at low RPM. At altitude we can typically run 20 psi of boost without endangering the engine, since the absolute manifold pressure is still below what it would be on a slightly tuned stock car at sea level running 16.3 psi. The problem is in the turbo's compressor map (tho none exist for the VF series). 20 psi at altitude is a high pressure ratio (2.8). That high of pressure ratio pushes the speed of the turbo up, near the limits (if we knew what the limits were). Turbos get more of a workout, increasing the chances of them failing. Watch for oil consumption getting out of hand. It can mean failing turbo bearings. High altitude (high pressure ratio) turbos can last longer in this service, and provide better results. And get used to lag. You thought it was bad, but you had no idea.

ktmrider - Sluggishness, especially if you can tell it's worse in open loop, is probably due to a mixture that's too rich. I suggest you get some wideband readings, whether installed and on the road, or even a tail pipe sniffer on a dyno. Tailpipe will run around 1.0 to 1.5 more lean than pre-cat, but you'll get an idea how rich it's running. Are you tuned, or is this the ECU? If you're just getting used to turbo lag, then welcome to the club. De-restricting your uppipe and exhaust will help immensely.

Thx, you're right on the turbo lag. My previous vehicle was a 5.7L Hemi truck with a 2600 stall. All the years of V8 pushrod engines has me jaded ( at least off the line ). The AWD and 4EAT are not helping my butt dyno either.
On the open loop stuff, I did the home made grounding mod and seafoamed the engine, fuel system, and crankcase. Although I made 3 changes at once ( synthetic oil change ) I believe the grounding mod was the key. The car idles smooth as glass, first tank fuel mileage went up from 20 to 23, and it runs perfectly in open loop/when cold. I was extremely skeptical about the ground stuff but since I had a few hours watching the kiddos one morning I decided to do it. $15 and 1 hour later I'm all smiles!!!!

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